Therapeutic Trial of Fluoroscopic Interlaminar Epidural Steroid Injection for Axial Low Back Pain: Effectiveness and Outcome Predictors

BACKGROUND AND PURPOSE: An ESI for managing LBP is one of the most commonly performed interventions. The purpose of this observational study was to assess the effect of a therapeutic trial of a fluoroscopic interlaminar ESI for axial LBP and to analyze the outcome predictors. MATERIALS AND METHODS: All patients who received an interlaminar ESI for axial LBP at our facility in 2007 and 2008 were included. Initial short-term follow-up was done at <1 month after ESI. ESI was considered effective if patients had a reduction of >50% in their pain scores. In July 2009, telephone interviews were conducted by using formatted questions including the NASS patient-satisfaction index. The symptom-free interval was computed by the Kaplan-Meier method. Outcome predictors such as age, sex, duration of LBP, and MR imaging findings were statistically analyzed by the Mann-Whitney U and the Fisher exact tests. RESULTS: Eighty-one patients (male/female = 16:65; mean age, 49.9 years; range, 17-77 years) were included in the study. The interlaminar ESI was effective in 63 of the 81 patients (77.8%) at initial short-term follow-up. For the 63 patients in whom ESI was effective, the median symptom-free interval was 154 days (95% CI, 96-212 days). Among 68 patients for whom telephone interviews were possible, 44 patients (64.7%) replied positively to the NASS patient satisfaction index (NASS patient-satisfaction index, 1 or 2). There were no significant outcome predictors. CONCLUSIONS: The therapeutic trial of a fluoroscopic interlaminar ESI was effective for axial LBP without significant outcome predictors.